University of Maryland Physics Professor Steve Rolston has been named chair of the Department of Physics effective July 1, 2016.
“I am excited and delighted to continue the department’s upward trajectory and strengthen its commitment to excellent research and to excellent education,” says Rolston.
"A HAWC eye on the sky" takes you on an audiovisual tour of a striking new astrophysics facility in Mexico. The High-Altitude Water Cherenkov (HAWC) gamma-ray observatory – which was inaugurated last year – is designed to catch a glimpse of some of the most extreme events in the cosmos. Located near the peak of the extinct Sierra Negra volcano, HAWC cuts a spooky image against the Mexican countryside, comprising 300 giant silver barrels with yellow tops that are filled with water.
Professor Johnpierre Paglione has been appointed as the new Director of the Center for Nanophysics and Advanced Materials. Having contributed to several fields of condensed matter research through both single-crystal synthesis of superconducting, quantum-critical and topological materials, as well as exploration of novel phenomena, he will continue to ensure the strength and vitality of the experimental condensed matter physics research performed in the Center.
Professor Paglione is a leader in the field of quantum criticality and has made important contributions to the fields of heavy-fermion materials and the quasiparticle picture of correlated materials. His team has more recently pursued several new areas of research including iron-based high-temperature superconductivity and topological insulators and superconductors. He is the recipient of a National Postdoctoral Fellowship Award from the Natural Sciences and Engineering Council of Canada, a National Science Foundation CAREER Award and an Early Career Award from the Department of Energy, and a recipient of the Gordon and Betty Moore Foundation Materials Synthesis Award. Dr. Paglione earned his PhD from the University of Toronto in Canada.
Theoretical physicists studying the behavior of ultra-cold atoms have discovered a new source of friction, dispensing with a century-old paradox in the process. Their prediction, which experimenters may soon try to verify, was reported recently in Physical Review Letters.
The friction afflicts certain arrangements of atoms in a Bose-Einstein Condensate (BEC), a quantum state of matter in which the atoms behave in lockstep. In this state, well-tuned magnetic fields can cause the atoms to attract one another and even bunch together, forming a single composite particle known as a soliton.
Solitons appear in many areas of physics and are exceptionally stable. They can travel freely, without losing energy or dispersing, allowing theorists to treat them like everyday, non-quantum objects. Solitons composed of photons—rather than atoms—are even used for communication over optical fibers.
Studying the theoretical properties of solitons can be a fruitful avenue of research, notes Dmitry Efimkin, the lead author of the paper and a former JQI postdoctoral researcher now at the University of Texas at Austin. “Friction is very fundamental, and quantum mechanics is now quite a well-tested theory,” Efimkin says. “This work investigates the problem of quantum friction for solitons and marries these two fundamental areas of research.”
Efimkin, along with JQI Fellow Victor Galitski and Johannes Hofmann, a physicist at the University of Cambridge, sought to answer a basic question about soliton BECs: Does an idealized model of a soliton have any intrinsic friction?
Prior studies seemed to say no. Friction arising from billiard-ball-like collisions between a soliton and stray quantum particles was a possibility, but the mathematics prohibited it. For a long time, then, theorists believed that the soliton moved through its cloudy quantum surroundings essentially untouched.